<p>
  Book-to-market ratio is used to find the value of a company by comparing the book value of a firm to its market value. The definition of the book-to-market ratio is
  \[Book\ to\ Market \ Ratio=\frac{Common\ Shareholders \ Equity}{Market \ Cap}=\frac{book \ value \ per \ share}{Market \ price \ per \ share}\]
  Book value represents a company's assets minus its liabilities and sometimes is referred to as shareholders' equity.
  Price-to-Book Ratio is defined as
  \[Price \ to \ Book\ Ratio=\frac{Market \ price \ per \ share}{book \ value \ per \ share}\]
  Therefore, we can see the Book-to-market ratio is the inverse of the P/B ratio.
  The book-to-market ratio suggests how much investors are paying against each dollar of book value in the balance sheet. 
  The bigger the ratio is, the more fundamentally cheap is the investigated company. This algorithm will create the portfolio with this factor.
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